netty: Possible direct memory leak

Expected behavior

Working normally with constant memory consumption

Actual behavior

Memory keep growing and eventually ends out of memory

Steps to reproduce

I have an application which creates 1500 connections every seconds. Memory consumption keep increasing and eventually ends out of memory. I monitored the heap whith many tools (jvisualvm, jmap, jcmd) and it looks ok. Insetad, java internal memory looks the probelem. I suspect it is a problem with netty because adding “-Dio.netty.tryUnsafe=false” to java parameters solves the issue (memory keeps steady and stable)

Netty version

4.1.16-final

JVM version (e.g. java -version)

openjdk version “1.8.0_111” OpenJDK Runtime Environment (build 1.8.0_111-8u111-b14-2~bpo8+1-b14) OpenJDK 64-Bit Server VM (build 25.111-b14, mixed mode)

OS version (e.g. uname -a)

Linux CR1 4.4.0-47-generic #68-Ubuntu SMP Wed Oct 26 19:39:52 UTC 2016 x86_64 GNU/Linux in a docker container